Sediment erosion and transport is critical to the ecological and commercial health of aquatic habitats from watershed to sea. There is now a consensus that microorganisms inhabiting the system mediate the erosive response of natural sediments ('ecosystem engineers') along with physicochemical properties. The biological mechanism is through secretion of a microbial organic glue (EPS: extracellular polymeric substances) that enhances binding forces between sediment grains to impact sediment stability and post-entrainment flocculation. The proposed work will elucidate the functional capability of heterotrophic bacteria, cyanobacteria and eukaryotic microalgae for mediating freshwater sediments to influence sediment erosion and transport. The potential and relevance of natural biofilms to provide this important 'ecosystem service' will be investigated for different niches in a freshwater habitat. Thereby, variations of the EPS 'quality' and 'quantity' to influence cohesion within sediments and flocs will be related to shifts in biofilm composition, sediment characteristics (e.g. organic background) and varying abiotic conditions (e.g. light, hydrodynamic regime) in the water body. Thus, the proposed interdisciplinary work will contribute to a conceptual understanding of microbial sediment engineering that represents an important ecosystem function in freshwater habitats. The research has wide implications for the water framework directive and sediment management strategies.
When released into surface waters, engineered inorganic nanoparticles (EINP) can be subject to multiple transformations. The objectives of MASK are to understand under which conditions EINP in aquatic systems will attach to suspended matter, under which conditions and in which time scale EINP are coated by NOM present in freshwater systems, how these coated colloidal particles are stabilized in the aquatic system and to which extent the aquatic aging processes are reversible. Homo-aggregation, coating changes, biological interactions and hetero-aggregation are hypothesized as key processes governing EINP aging in water bodies. In process orientated laboratory incubation experiments (50 ml to 6 l) with increasing complexity, MASK unravels the relevance and the interplay of inorganic colloids, aquagenic and pedogenic organic matter and solution physicochemistry for stability of EINP. These systems will successively approach situations in real waters. MASK thus provides information on EINP fluxes in the aquatic compartment, their time scales, reversibility and relative relevance. EINP will be analysed by standard light scattering techniques, ICP-MS, ESEM/EDX, WetSTEM and AFM. A method coupling hydrodynamic radius chromatography (HDC) with ICPMS recently developed by K. Tiede for nAg0 will be optimized and developed for further EINP analysis, MASK is further responsible for the virtual subproject ANALYSIS, the development and optimization of joint research unit methods of EINP analysis, sample preparation and sample storage, the exchange of methods and coordinates the joint analyses and the central EINP database.
Beach sand deposits are widespread in the area around Sandefjord, at the western coast of the Oslofjord, southern Norway. The age of the deposits continuously increases with elevation, as the area has been subject to steady glacio-isostatic uplift throughout the Holocene. Existing local sea level curves provide age control related to elevation. Thus, the area offers excellent conditions to test hypotheses on soil formation and OSL dating. A chronosequence covering the last 10 000 years will be established. A preliminary study showed that soil formation leads to Podzols within 4300 - 6600 years. Micromorphological analyses suggest that clay illuviation takes place before and below podzolisation. It is hypothesised that clay translocation goes on contemporarily with podzolisation, but at greater soil depth, where the chemical conditions are suitable. This hypothesis will be proved by more detailed micromorphological investigation and chemical analyses. The factors controlling soil forming processes and their rates, will be determined by analyzing elemental composition, primary minerals and clay mineralogy. Preliminary OSL dating tests suggest that the beach sand deposits are OSL dateable despite the high latitude. This hypothesis will be checked by comparing OSL datings to ages derived from the 14C-based sea level curves.
In the last decades agricultural policy has gained increasingly in complexity. Nowadays it influences the food and agricultural sector from the global market down to the farm level. Widespread research questions, like the impact of the WTO negotiations on the farm structure, most often require comprehensive modeling frameworks. Thus, different types of models are utilized according to their comparative advantages and combined in a strategically useful way to more accurately represent micro and macro aspects of the food and agricultural sector. Consequently, in recent years we have seen an increase in the development and application of model linkages. Given this background, the overall objective of this subproject is a systematic sensitivity analysis of model linkages that gradually involves more and more characteristics of the linkage and the corresponding transfer of results between models. In addition, the project aims to answer the following specific question: How does structural change at the farm level influence aggregate supply and technical progress? Under which conditions is it possible to derive macro-relationships from micro-relationships? How does the aggregation level influence the model results and how can possible problems be overcome? This procedure is used to quantify the effects and to derive conditions for optimal interaction of the connected models. The analysis is based on the general equilibrium model GTAP (Global Trade Analysis Project) and the farm group model FARMIS (Farm Modelling Information System) which are employed in conjunction to analyze the effects of WTO negotiations on the farm level.
Organotin and especially butyltin compounds are used for a variety of applications, e.g. as biocides, stabilizers, catalysts and intermediates in chemical syntheses. Tributyltin (TBT) compounds exhibit the greatest toxicity of all organotins and have even been characterized as one of the most toxic groups of xenobiotics ever produced and deliberately introduced into the environment. TBT is not only used as an active biocidal compound in antifouling paints, which are designed to prevent marine and freshwater biota from settlement on ship hulls, harbour and offshore installations, but also as a biocide in wood preservatives, textiles, dispersion paints and agricultural pesticides. Additionally, it occurs as a by-product of mono- (MBT) and dibutyltin (DBT) compounds, which are used as UV stabilizer in many plastics and for other applications. Triphenyltin (TPT) compounds are also used as the active biocide in antifouling paints outside Europe and furthermore as an agricultural fungicide since the early 1960s to combat a range of fungal diseases in various crops, particularly potato blight, leaf spot and powdery mildew on sugar beet, peanuts and celery, other fungi on hop, brown rust on beans, grey moulds on onions, rice blast and coffee leaf rust. Although the use of TBT and TPT was regulated in many countries world-wide from restrictions for certain applications to a total ban, these compounds are still present in the environment. In the early 1970s the impact of TBT on nontarget organisms became apparent. Among the broad variety of malformations caused by TBT in aquatic animals, molluscs have been found to be an extremely sensitive group of invertebrates and no other pathological condition produced by TBT at relative low concentrations rivals that of the imposex phenomenon in prosobranch gastropods speaking in terms of sensitivity. TBT induces imposex in marine prosobranchs at concentrations as low as 0,5 ng TBT-Sn/L. Since 1993, for the littorinid snail Littorina littorea a second virilisation phenomenon, termed intersex, is known. In female specimens affected by intersex the pallial oviduct is transformed of towards a male morphology with a final supplanting of female organs by the corresponding male formations. Imposex and intersex are morphological alterations caused by a chronic exposure to ultra-trace concentrations of TBT. A biological effect monitoring offers the possibility to determine the degree of contamination with organotin compounds in the aquatic environment and especially in coastal waters without using any expensive analytical methods. Furthermore, the biological effect monitoring allows an assessment of the existing TBT pollution on the basis of biological effects. Such results are normally more relevant for the ecosystem than pure analytical data. usw.
The sorption of anions in geotechnical multibarrier systems of planned high level waste repositories (HLWR) and of non-ionic and organic pollutants in conventional waste disposals are in the center of recent research. In aquatic systems, persistent radionuclides such as 79Se, 99Tc, 129I exist in a form of anions. There is strongly increasing need to find materials with high sorption capacities for such pollutants. Specific requirements on barrier materials are long-term stability of adsorbent under various conditions such as T > 100 C, varying hydrostatic pressure, and the presence of competing ions. Organo-clays are capable to sorb high amounts of cations, anions and non-polar molecules simultaneously having selectivity for certain ions. This project is proposed to improve the understanding of sorption and desorption processes in organo-clays. Additionally, the modification of material properties under varying chemical and thermal conditions will be determined by performing diffusion and advection experiments. Changes by sorption and diffusion will be analyzed by determining surface charge and contact angles. Molecular simulations on models of organo-clays will be conducted in an accord with experiments with aim to understand and analyze experimental results. The computational part of the project will profit from the collaboration of German partner with the group in Vienna, which has a long standing experience in a modeling of clay minerals.
Iron(III) (hydr)oxide-organic associations in soils have been recognized to play an important role in the biogeochemical cycling of iron, carbon, and of nutrients like phosphate. In temporarily moist or water-logged soils such associations can form via the coprecipitation of dissolved organic matter (OM) with Fe(III) (hydr)oxides (FHOs). At present, it is generally unknown which factors control the formation and composition of Fe(III)-OM coprecipitates and how the structural properties translate into the cycling of the FHO and OM component involved. The objectives of the project are thus to elucidate (i) the structural properties of Fe(III)- OM coprecipitates under different environmental conditions, (ii) the subsequent stability of Fe(III)-OM coprecipitates against dissolution under both oxic as well as anoxic conditions, (iii) the changes in Fe(III)-OM coprecipitate composition upon redox oscillations, and (iii) their cumulative effects on oxyanion sorption. To achieve these goals, various batch experiments will be conducted. By using multiple analytical tools, this project will gain a fundamental understanding of the abiotic and biotic controls on the formation, structure, and biogeochemical reactivity of Fe(III)-OM coprecipitates in acidic and neutral temporarily moist soils and soils subject to redox oscillations.
Magnetic properties of ferrimagnetic minerals depend on their crystal lattice, anisotropy, chemical composition and grain size. The latter parameter is strongly controlled by microstructures, which are significant for the interpretation of the magnetic properties of shocked magnetic minerals. Fracturing and lattice defects are the main causes for magnetic domain size reduction and generate an increase in coercivity and the suppression of magnetic transitions (e.g. 34 K transition in pyrrhotite, Verwey transition in magnetite).Especially for an adequate investigation of shock-induced modifications in ferromagnetic minerals, a combination of microstructural and magnetic measurements is therefore essential.This project focusses on two significant aspects of extreme conditions - the consequence of shock waves on natural material on Earth and on the magnetic mineralogy of exotic magnetic minerals in iron meteorites. In order to obtain general correlations between deformation structures and magnetic properties, the specific magnetic properties and carriers as well as microstructures of samples from two impact structures in marine targets (Lockne and Chesapeake Bay) will be compared with shocked magnetite ore and magnetite-bearing target lithologies from outside the crater (Lockne) as well as from undeformed megablocks within the crater (Chesapeake Bay). We will test the hypothesis if shock-related microstructures and associated magnetic properties can significantly be overprinted by postshock hydrothermal alteration. We especially want to focus on the Verwey transition (TV) as lower TVs are described for shocked impact lithologies. Hence, the main focus of this study lies on magneto-mineralogical investigations which combine low- and high-temperature magnetic susceptibility and saturation isothermal remanent magnetization with mineralogical and microstructural investigations. The same methods will then be used for the investigation of iron meteorites, whose magnetic properties are often controled by exotic magnetic minerals like cohenite, schreibersite and daubreelite in addition to the metal phases. Magnetic transition temperatures of those phases are poorly documented in relation to their chemical composition as well as to their crystallographic and microstructural configuration. For a general understanding of shock-related magnetization processes in extraterrestrial and terrestrial material, however, it is crucial to obtain a general correlation between the initial 'unshocked' state and the subsequent shock- and alteration-related overprints.
Calcium supply in tropical soils is variable and frequently low. In spite of the heterogeneous Ca supply, some plant species, such as figs, maintain high Ca concentrations in their tissues. Figs are keystone species with more than proportional importance for the functioning of a tropical rain forest. High Ca concentrations in fig fruits may render them particularly attractive for frugivorous vertebrates. We propose to study the whole Ca cycling from soil through a selected fig species, Ficus insipida Willd. and frugivorous bats, their main dispersers, back to soil. The study will be conducted in Panama on sites differing in soil Ca status to assess the importance of soil Ca availability for fig fruit content and bat reproduction. We will quantify aboveground Ca fluxes for 16 trees along a gradient of Ca availability in soil. We will determine (1) Ca concentrations in soils, figs and leaves, (2) nutritional quality of fig and other bat-dispersed fruits and their importance for Ca balance in relation to reproduction of fruit-eating bats, (3) Ca fluxes with litterfall, throughfall, stemflow, bat pellets and faeces, (4) the importance of the contribution of bats to the Ca cycle of individual fig trees, and (5) the effect of fig trees on soil Ca concentrations.
Zielsetzung und Anlass des Vorhabens: Ziel der letzten Projektphase war es, mit einer Langzeit-Praxiserprobung das zweistufige biologische Verfahren zur Deponiesickerwasserreinigung als Stand der Technik zu etablieren und zu bilanzieren. Nach der Inbetriebnahme des Technikums am Deponiestandort Schöneiche ging es in der zwölfmonatigen Laufzeit des Projektes AZ 14996/04 in den Langzeitversuchen um die Validierung der Laborergebnisse im technischen Maßstab, die verfahrenstechnische Optimierung der Anlage und um eine damit verbundene mögliche Kostenreduzierung des Systems. Darstellung der Arbeitsschritte und der angewandten Methoden: Nach dem ersten Technikums-Probebetrieb wurde eine Reihe von Optimierungsmaßnahmen durchgeführt: - der Umbau des Rohsickerwasserzulaufs, - die Verwendung von Soda statt Bicarbonat für die Ammoniumoxidation in Reaktor 2, - der Einsatz von Membrandosierpumpen mit integrierten Rückschlagventilen für die Zugabe von Soda und Essigsäure, - der Einbau von zusätzlichen Polyurethan-Festbetten zur Vergrößerung der Oberfläche für die Besiedlung mit Mikroorganismen, - die Einstellung des Sollwerts für Reaktor 4 auf einen pH-Wert von 6,5, - ein Update der SPS-Steuerung der Nanofiltration zur freien Programmierung der Spülzyklen, - der Einbau eines Absperrhahns vor den Nanofiltrations-Vorfilter - und die Trennung des Nanofiltrationsablaufs vom Reaktoren-Sammelablauf zur Behälterleerung. Es wurde sowohl Rohsickerwasser der MEAB-Deponie Schöneiche als auch Sickerwasserkonzentrat der Deponie Vorketzin behandelt. Fazit: Wegen der durchgeführten Optimierungsmaßnahmen ist es prinzipiell gelungen, das Schöneicher Rohsickerwasser gemäß Anhang 51 der Abwasserverordnung aufzureinigen. In Vorketzin wurde die organische Belastung über 70% und Stickstoff über 80% reduziert. Nach Rückgang der Calciumfracht sollte es zukünftig möglich sein, mit der Zweistufen-Biologie das Sickerwasserkonzentrat ausreichend zu reinigen, da organische Belastung und Stickstoffgehalt geringer als im Schöneicher Rohsickerwasser sind. Um das Verfahren als Stand der Technik, vor allem für die Behandlung von Sickerwasserkonzentraten, zu etablieren, müssten die Laborvorgaben mit den Erfahrungen des Technikumsbetriebs kombiniert und in einer weiteren Versuchsreihe unter optimierten Bedingungen verifiziert werden.
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